2.  We need to look into cells for the answer  Analyzing chromsomes enables biologists to look at the human genome  Karyotype is a picture of chromosomes arranged in a specific way  Photograph cells in mitosis  Fully condensed chromosomes are easy to see  Cut chromosomes out of the photograph  Group them in pairs  Cells for karyotypes are taken by procedures like amniocentesis for unborn children

3.  46 chromosomes in human cell  Sex chromosomes  Autosomes: all other chromosomes except sex chromosomes Animation

4.  These are useful for determining sex of an unborn child  Determining diseases caused by chromosomal mutations  Most common error in mitosis is called “nondisjunction”  This is the failure of homologous chromosomes to separate during meiosis I  Causes abnormal numbers of chromosomes  Other mutations are deletions, translocations, duplications, and inversions

5.  Two copies of an autosomal chromosome fail to separate in the gametes  Individual born with three copies of a chromosome, “trisomy”  Patau Syndrome – trisomy of chromosome 13- results in Mental retardation and minor physical deformaties

6.  Two copies of an autosomal chromosome fail to separate  Causing an individual to be born with three copies of a chromosome, “trisomy”  Down’s syndrome is three copies of chromosome 21  In the US, 1 in 800 children are born with this disorder  Produces mild to severe mental retardation, increased susceptibility to other diseases, higher frequency of birth defects

7.  Turner’s Syndrome  Only occurs in females  Characterized by missing an “X” chromosome (karyotype 45, X)  Women with Turner’s are sterile, sex organs do not develop  Klinefelter’s Syndrome  Only occurs in males  Characterized by an extra “X” chromosome (karyotype 47, XXY or XXXY)  Men with Kleinfelter’s are sterile

9.  Genes are inherited according to Mendel’s principles of heredity  However, in order to apply to human traits, biologists must identify what traits are controlled by which genes  Pedigrees are charts that show relationships between families  Pedigree charts can show the relationships between traits of many generations of families

11.  Human traits are almost impossible to associate with one gene  Genetic counselors use pedigrees to make assumptions about inheritance of genes  However, environment effects the expression of many genes  Genes can be influences by nutrition and exercise  Environmental effects on genes ARE NOT inherited

12.  Human genome consists of thousands of genes  Studying this is not easy, due to long generation time, complex life cycle, production of very few offspring  Biologist were able to identify genes that control human traits  One of the first genes identified was human blood  Concept Map #4 Time!!!!!

13.  Phenotypes A, B, AB, O  Genotype (A) I A I A, I A i  Genotype (B) I B I B, I B i  Genotype (AB) I A I B  Genotype (O) ii  Type O is the universal donor  Type AB is the universal recipient

14.  Identification of genes shows many recessive alleles and disorders caused by them  If the genotype has one functioning gene, the disease will not show  Recessive disorders are caused by having two copies of the defective gene  PKU-lack enzyme needed to break down phenylalanine  Causes severe mental retardation when this enzyme builds up (chromosome 12)

15.  When dominant allele is present the disorder is shown in the individual  Dwarfism and Huntington’s Disease are caused by a Dominant allele  Codominant alleles: disorders caused by a heterozygous condition  Example: Sickle Cell Disease

16.  Some are issues of misfolded proteins which affects the structure and purpose of the protein  Cystic Fibrosis: caused by recessive allele on chromosome 7  Caused by deletion of (3) bases in the middle of a sequence of a protein, causing misfolding  Characterized by digestive problems, thick, heavy mucus that clogs the lungs  Sickle Cell Disease: Caused by one base change in the hemoglobin protein that carries oxygen, result abnormal hemoglobin

17.  Sex Linked Genes: genes located on X chromosome or Y chromosome  Causes Sex Linked genetic disorders  X-Chromosome contains genes for survival  Y-Chromosome contains genes for maleness  Determining sex of unborn children can be done using a Punnett Square for probabilities  Determine sex linked disorders using punnett squares for probabilities

18.  Sex linked disorder carried on X-chromosome  Gene helps control blood clotting  Recessive allele present on gene can cause the disorder  Protein necessary for normal blood clotting is missing  Muscular Dystrophy  Caused by defective gene that codes for muscle protein  Progressive weakening and loss of skeletal muscle

19.  If parents suspect they are carrying a disorder, they can find out using many different ways  Genetic tests are available for many disorders  Karyotyping  DNA fingerprinting: analysis of genes that are introns (sections that do not code for anything)  This area is the area that we all differ the most Get DNA from blood, semen, saliva, urine, skin, hair, etc Used for Identification of suspects, parents, dead bodies, diseases

20.  Project began in 1990  Designed to analyze the human DNA sequence  In June 2000, scientists announced a working copy of human genome was complete

21.  An absent or faulty gene is replaced by a normal, working gene  This can correct the protein needed eliminating the cause of the disorder  Scientists do not yet know the benefits of this type of treatment  Or if it will last through the lifetime of the individual  Viruses are often used to get into the cell’s DNA  Virus’s DNA is modified so they do not cause disease

22.  A DNA fragment containing the replacement gene is spliced into the viral DNA  The patient is infected with the virus which should carry the replacement gene to the cells to correct the genetic defects  What will happen to the human species if we gain the opportunity to design our bodies???  Interactive Review Concept Map